为树莓派3B添加LCD1602液晶屏-白红宇

为树莓派3B添加LCD1602液晶屏

阅读量：5249 次

发布时间：2019-06-14

本文共 8700 字，大约阅读时间需要 29 分钟。

树莓派3B针脚说明

LCD1602接线说明

VSS，接地

VDD，接5V电源

VO，液晶对比度调节，接电位器中间的引脚，电位器两边的引脚分别接5V和接地。

RS，寄存器选择，接GPIO14

RW，读写选择，接地，表示写模式

EN，使能信号，接GPIO15

D0，数据位0，4位工作模式下不用，不接

D1，数据位1，4位工作模式下不用，不接

D2，数据位2，4位工作模式下不用，不接

D3，数据位3，4位工作模式下不用，不接

D4，数据位4，接GPIO17

D5，数据位5，接GPIO18

D6，数据位6，接GPIO27

D7，数据位7，接GPIO22

A，液晶屏背光+，接5V

K，液晶屏背光-，接地

调整电位器

　　因为缺少1个5V的线，直接破皮拧一根进去就行，电位器调整到屏幕显示正常的对比度即可，第一次玩烙铁，焊的略丑…

lcd1602.py

#!/usr/bin/python ## based on code from lrvick and LiquidCrystal# lrvic - https://github.com/lrvick/raspi-hd44780/blob/master/hd44780.py# LiquidCrystal - https://github.com/arduino/Arduino/blob/master/libraries/LiquidCrystal/LiquidCrystal.cpp# from time import sleep class lcd1602:     # commands    LCD_CLEARDISPLAY 		= 0x01    LCD_RETURNHOME 		= 0x02    LCD_ENTRYMODESET 		= 0x04    LCD_DISPLAYCONTROL 		= 0x08    LCD_CURSORSHIFT 		= 0x10    LCD_FUNCTIONSET 		= 0x20    LCD_SETCGRAMADDR 		= 0x40    LCD_SETDDRAMADDR 		= 0x80     # flags for display entry mode    LCD_ENTRYRIGHT 		= 0x00    LCD_ENTRYLEFT 		= 0x02    LCD_ENTRYSHIFTINCREMENT 	= 0x01    LCD_ENTRYSHIFTDECREMENT 	= 0x00     # flags for display on/off control    LCD_DISPLAYON 		= 0x04    LCD_DISPLAYOFF 		= 0x00    LCD_CURSORON 		= 0x02    LCD_CURSOROFF 		= 0x00    LCD_BLINKON 		= 0x01    LCD_BLINKOFF 		= 0x00     # flags for display/cursor shift    LCD_DISPLAYMOVE 		= 0x08    LCD_CURSORMOVE 		= 0x00     # flags for display/cursor shift    LCD_DISPLAYMOVE 		= 0x08    LCD_CURSORMOVE 		= 0x00    LCD_MOVERIGHT 		= 0x04    LCD_MOVELEFT 		= 0x00     # flags for function set    LCD_8BITMODE 		= 0x10    LCD_4BITMODE 		= 0x00    LCD_2LINE 			= 0x08    LCD_1LINE 			= 0x00    LCD_5x10DOTS 		= 0x04    LCD_5x8DOTS 		= 0x00       def __init__(self, pin_rs=14, pin_e=15, pins_db=[17, 18, 27, 22], GPIO = None):	# Emulate the old behavior of using RPi.GPIO if we haven't been given	# an explicit GPIO interface to use	if not GPIO:	    import RPi.GPIO as GPIO   	self.GPIO = GPIO        self.pin_rs = pin_rs        self.pin_e = pin_e        self.pins_db = pins_db         self.GPIO.setmode(GPIO.BCM)        self.GPIO.setwarnings(False)        self.GPIO.setup(self.pin_e, GPIO.OUT)        self.GPIO.setup(self.pin_rs, GPIO.OUT) 	for pin in self.pins_db:            self.GPIO.setup(pin, GPIO.OUT) 	self.write4bits(0x33) # initialization	self.write4bits(0x32) # initialization	self.write4bits(0x28) # 2 line 5x7 matrix	self.write4bits(0x0C) # turn cursor off 0x0E to enable cursor	self.write4bits(0x06) # shift cursor right 	self.displaycontrol = self.LCD_DISPLAYON | self.LCD_CURSOROFF | self.LCD_BLINKOFF 	self.displayfunction = self.LCD_4BITMODE | self.LCD_1LINE | self.LCD_5x8DOTS	self.displayfunction |= self.LCD_2LINE 	""" Initialize to default text direction (for romance languages) """	self.displaymode =  self.LCD_ENTRYLEFT | self.LCD_ENTRYSHIFTDECREMENT	self.write4bits(self.LCD_ENTRYMODESET | self.displaymode) #  set the entry mode         self.clear()      def begin(self, cols, lines): 	if (lines > 1):		self.numlines = lines    		self.displayfunction |= self.LCD_2LINE		self.currline = 0      def home(self): 	self.write4bits(self.LCD_RETURNHOME) # set cursor position to zero	self.delayMicroseconds(3000) # this command takes a long time!      def clear(self): 	self.write4bits(self.LCD_CLEARDISPLAY) # command to clear display	self.delayMicroseconds(3000)	# 3000 microsecond sleep, clearing the display takes a long time      def setCursor(self, col, row): 	self.row_offsets = [ 0x00, 0x40, 0x14, 0x54 ] 	if ( row > self.numlines ): 		row = self.numlines - 1 # we count rows starting w/0 	self.write4bits(self.LCD_SETDDRAMADDR | (col + self.row_offsets[row]))      def noDisplay(self): 	""" Turn the display off (quickly) """ 	self.displaycontrol &= ~self.LCD_DISPLAYON	self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)      def display(self):	""" Turn the display on (quickly) """ 	self.displaycontrol |= self.LCD_DISPLAYON	self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)      def noCursor(self):	""" Turns the underline cursor on/off """ 	self.displaycontrol &= ~self.LCD_CURSORON	self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)      def cursor(self):	""" Cursor On """ 	self.displaycontrol |= self.LCD_CURSORON	self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)      def noBlink(self):	""" Turn on and off the blinking cursor """ 	self.displaycontrol &= ~self.LCD_BLINKON	self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)      def noBlink(self):	""" Turn on and off the blinking cursor """ 	self.displaycontrol &= ~self.LCD_BLINKON	self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)      def DisplayLeft(self):	""" These commands scroll the display without changing the RAM """ 	self.write4bits(self.LCD_CURSORSHIFT | self.LCD_DISPLAYMOVE | self.LCD_MOVELEFT)      def scrollDisplayRight(self):	""" These commands scroll the display without changing the RAM """ 	self.write4bits(self.LCD_CURSORSHIFT | self.LCD_DISPLAYMOVE | self.LCD_MOVERIGHT);      def leftToRight(self):	""" This is for text that flows Left to Right """ 	self.displaymode |= self.LCD_ENTRYLEFT	self.write4bits(self.LCD_ENTRYMODESET | self.displaymode);      def rightToLeft(self):	""" This is for text that flows Right to Left """	self.displaymode &= ~self.LCD_ENTRYLEFT	self.write4bits(self.LCD_ENTRYMODESET | self.displaymode)      def autoscroll(self):	""" This will 'right justify' text from the cursor """ 	self.displaymode |= self.LCD_ENTRYSHIFTINCREMENT	self.write4bits(self.LCD_ENTRYMODESET | self.displaymode)      def noAutoscroll(self): 	""" This will 'left justify' text from the cursor """ 	self.displaymode &= ~self.LCD_ENTRYSHIFTINCREMENT	self.write4bits(self.LCD_ENTRYMODESET | self.displaymode)      def write4bits(self, bits, char_mode=False):        """ Send command to LCD """ 	self.delayMicroseconds(1000) # 1000 microsecond sleep         bits=bin(bits)[2:].zfill(8)         self.GPIO.output(self.pin_rs, char_mode)         for pin in self.pins_db:            self.GPIO.output(pin, False)         for i in range(4):            if bits[i] == "1":                self.GPIO.output(self.pins_db[::-1][i], True) 	self.pulseEnable()         for pin in self.pins_db:            self.GPIO.output(pin, False)         for i in range(4,8):            if bits[i] == "1":                self.GPIO.output(self.pins_db[::-1][i-4], True) 	self.pulseEnable()      def delayMicroseconds(self, microseconds):	seconds = microseconds / float(1000000)	# divide microseconds by 1 million for seconds	sleep(seconds)      def pulseEnable(self):	self.GPIO.output(self.pin_e, False)	self.delayMicroseconds(1)		# 1 microsecond pause - enable pulse must be > 450ns 	self.GPIO.output(self.pin_e, True)	self.delayMicroseconds(1)		# 1 microsecond pause - enable pulse must be > 450ns 	self.GPIO.output(self.pin_e, False)	self.delayMicroseconds(1)		# commands need > 37us to settle      def message(self, text):        """ Send string to LCD. Newline wraps to second line"""         for char in text:            if char == '\n':                self.write4bits(0xC0) # next line            else:                self.write4bits(ord(char),True)  if __name__ == '__main__':     lcd = lcd1602()    lcd.clear()    lcd.message("hello world!")

1602.py

#!/usr/bin/python from lcd1602 import *from datetime import *import commands def get_cpu_temp():    tmp = open('/sys/class/thermal/thermal_zone0/temp')    cpu = tmp.read()    tmp.close()    return '{:.2f}'.format( float(cpu)/1000 ) + ' C' def get_gpu_temp():    tmp = commands.getoutput('vcgencmd measure_temp|awk -F= \'{print $2}\'').replace('\'C','')    gpu = float(tmp)    return '{:.2f}'.format( gpu ) + ' C' def get_time_now():    return datetime.now().strftime('    %H:%M:%S\n   %Y-%m-%d') def get_ip_info():    return commands.getoutput('ifconfig wlan0|grep inet|awk -Faddr: \'{print $2}\'|awk \'{print $1}\'') def get_mem_info():    total= commands.getoutput('free -m|grep Mem:|awk \'{print $2}\'')      free = commands.getoutput('free -m|grep cache:|awk \'{print $4}\'')    return 'MEM:\n    ' + free +' / '+ total +' M' lcd = lcd1602()lcd.clear() if __name__ == '__main__':     while(1):        lcd.clear()        lcd.message( get_ip_info() )        sleep(5)         lcd.clear()        lcd.message( get_time_now() )        sleep(5)         lcd.clear()        lcd.message( get_mem_info() )        sleep(5)         lcd.clear()        lcd.message( 'CPU: ' + get_cpu_temp()+'\n' )        lcd.message( 'GPU: ' + get_gpu_temp() )        sleep(5)

　　将以上两个文件保存在同一个目录下，运行1602.py即可打印信息到LCD上。